Reversible circulation internal fan kiln



\ Aug. 28, 1923. I 4 553 R. THELEN REVERSIBLE GIRCULATIONINTERNAL FAN KILN Filed May 19, 1923 2 Sheets-Sheet l O0 O0 O0 0500 I N V EN TOR.

FIG. 5

A TTORNEKB.

Aug. 28, 1923.

R. THELEN REVERSIBLE CIRCULATION INTERNAL FAN KILN Filed May 19 1925 2 Sheets-Sheet 2 INVENTOR. EQLF- THELEN 5: ATTORNEYS.

Patented Aug. 2%, 1923..

UNITED STATES PATENT OFFICE.

ROLF THELEN OF MADISON, WISCONSIN, DEDICATED, BY MESNE ASSIGNMENTS, TO

7 THE CITIZENS OF THE UNITED. STATES OF AMERICA REYEBSI BLE'CIRCULATION INTERNAL FAN KILN.

Application filed. may 19. 1923. Serial No. 640,280.

mun manna rim Aer crimson 9,1883, 22 STALL, e25.

To all whom it may concern:

Be it known that I, ROLF THELEN, a citizen of the United States of America, and an employee of the Department of Agricul-' ture, residing in Madison, Wisconsin,-

(whose post-ofiice address is Madison, Wis- ,consim) have invented a'new and Improved Reversible Circulation Internal Fan Kiln.

This application is made under the act 10 of March 3, 1883, Chapter 143- (22 Stat. 625), and the invention herein described and claimed may be used by the Government of the United States, its ofiicers'and employees, and by any person in the United States 35 without the payment to me of any royalty thereon. I hereby dedicate the same to the free use of the Government and the people of the United States. Myhnvention consistsin an improvement in the design of forced circulation kilns or chambers for drying and conditioning lumher or similar material. However,its use is I not limited to wood or wood products. It consists in the adaptation of fans'of the disk type, or similar types, to the production of a unique internal circulation of air and'the vapor iithe kiln combined with the production and regulation of the heat and the humidity within the kiln. I v

This'invention is illustrated in Fi res 1 to 3. Figure 1 represents across-sectional elevation. Figure 2 represents a horizontal cross-section of the kiln taken directly ks-- neath the track support. Figure 3 represei is as avertieal longitudinal cross-section near the center of the kiln and shows in detail some ofthe air distributing system. v

I The principal feature which I claim as novel and an improvement over existing 1o kilns is the use and arrangement of the fans and the air distributing system.- This arrangement is such that a very fast and uniform circulation of air and vapor through the pile of lumber may be. secured and permits the periodic reversal of the direction of the air movement by simply reversing the direction of rotation oftheZfans. The air distributing system provides a very uniform flow of air throughout the length of o the "kiln ,and eliminates the non-uniformity of drying, which is one of the commonest trouble experienced in the ordinary kiln.

The arrangement of the fans upon a single shaft extending throughout the length of the ki1n provides a simple means of produclng a brisk circulation; and the eliminat1on of comparatively small ducts such as those used in external blower kilns reduces very materially the work required to pro-i.

duce a given circulation. The differences in air-pressure required in the operation of this vkiln are much smaller'than those ordinarily required in kilns' employing centrifugal blowers, and the disk fans operate very efficiently at these lowpressures. Itis possible, therefore, by the use of this invention to produce a very great and uniform circulation of air and vapor within the kiln with a very small. expenditure of power.

While it is obvious that there are many possible ways in whichthe use of internal fans can be adapted to drying kilns of, different types, this invention is limited to kilns in which the lumber is flat and piled and in which a single row of fans is emp y e a Any well-known means of heating the air and the vapor inthe kiln may beused in conjunction with this steam ipes are used they may be arranged beneat the lumber piles or in any other. convenient manner. Any convenient form and arrangement of heaters may be used.

The drawings show and the specificatlon describes steam jet pipes for increasing the humidity, and air inlet flues with suitable dampers for decreasing the humidity.

While the dra'wingsshow and the specification describes specificmeans for heating .theair and the vapor in the kiln and for regulating thehu'midity of the air in the kiln, this invention is not limited specifically tothe arrangements may make use of any other su table and well-known means for accomplrshmg the same purposes. While the drawings illustrate and the specification describes a spe'- cific form of flat end piled lumber, the m vention is not limited to this particular form since itis .equallyapPlicable to all other forms of flat end piling, such as sminvention. When described, but

glepiles with parallel-sided central ehimney and double piling with or without chimneys in each pile. It is also adapted to in-.

alasaaaaaararaa Asia clined piling in which the layers of lumber chimneys of other shapes, such, for instance, are inclined slightly from the horizontal to as chimneys withv arallel sides may be assist the air movement. used. WW are the side air passages whi'ch Referring to Figuresl, 2, and 3, which are ma likewise be of any well-known form as correspondingly lettered: AA represent the we 1 as of the form illustrated in the draw- 70 side deflecting partitions. These partitions ings and described in the specification. X serve to form a passageway for the air from is the main air distributor. YY are the up the heating coils to the fans when the air per diffusers and ZZ the lower diffusers. circulation is' in the direction indicated on The side deflecting partitions, the main air 1 Figure 1, and when the direction of the air distributor, and the two sets of 'di-flusers 75 circulation is in the opposite direction they form a single air deflecting and distributing serve to deflect the air delivered by the fans unit. toward the sides and over the heating coils. The operation of the kiln is briefly as BB are the fans producing the circulation. 'follows: The lumber is placed in the kiln,

Straight-bladed disk fans are preferable. the doors and all of the dampers are closed, 80 Any type of fan, however, in which the reand the kiln is started. Steam is-turned into versal of the direction of rotation of the fan the coils and one set of steam jets is turned produces a reversal in the direction of flow on. Suitable regulating devices are proof the air current passing through the fan vided to control and regulate the supply of can be used. C is the shaft upon which the steamto the heating coils and the supplyof 85 fans are mounted. Provision is made to take steam tothe steam jets. If it is found imcare of the expansion and contraction of possible to reduce the humidity to the dethis shaft with changes in the temperature sired point with the" steam jets all turned in the kiln. DD are air inlet dampers used oil, the dampers DD and 00 are opened to to regulate and control the amount of air enallow fresh air to enter and moist air to es 90 tering thekiln from the outside. EE are cape. These dampers are adjusted so that a the heating coils. The coils illustrated 1n humidity below that desired will be sethe drawings and described in the specifica 'cured.. The steam jets may then automatitionvare of the return bend type. This incally supply a suflicient amount of steam to vention is, however,.not limited to'this'type bring the humidity upto the desired point. 9" since any common or well-known type may If the direction of rotation of the motor, the be adapted to it. FF are the steam jet pipes shaft, and the fans is such that the air and usedto increase the humidity of the air in vapor pass upward through thecentral the kiln. The lower pair is used when the chimney V, the air and vapor will pass latcirculation of air and vaporis downward erally outward through the lumber into the 100 through the central chimney V and the upside passages WW, downward through these 'per pair is used when the circulation is in passages across the heating coils, past the the reverse direction. G is the lumber-supside deflecting partitions, through the fans porting truck,- HI-I are the shaft hangers. into the main air distributor which acts as 4d II are bearings for the shaft C. J J are the a plenum chamber, a slight pressure being 105) tracks upon which the lumber-supporting maintained through the action of the fans truck runs. Theinvention is not specifically and the resistance of the upper and lower limited to the form and arrangement of difi'users. The air then passes from the main lumber-supporting truck, tracks, and track air distributor through the lower diffuser support illustrated since any well-known Z. The-resistance ofthe upper diffuser Y method of supporting the lumber may be serves to maintain a slight plenum between used without influencing inany way the the upper and lower diffusers. The air efliciency or operation of the kiln. KK are then passes upward through the upper difthe side walls ofthe kiln. LL is the lumber fuser and into the central chimney, repeatto be dried. M is the track support. N is ing the cycle continuously. The use of the the shaft pulley. 00 are air outlet dampers two'sets of diffusers in the manner indicated for controlling the amount of air being eX- produces a very uniform flow of air throughhausted from the. kiln. P is a belt'passing out the'length of the kiln. The unbalancing over the pulleys N and Q. Q; is the motor effect of the horizontal air flow produced by pulley. R is the motorwhich furnishes the the fans is practically eliminated by allowpower to drive the fans. S is a switch for ing a slight pressure to build up in the main controlling the speed and rotation of the distributor. This is still further eliminated motorarmature. While the drawings show by the slight plenum in the space between and the specification describes an electric the upper and lower distributors. It is obmotor, any other suitable driving means may vious that the kiln would work reasonably 125 .be used. TTare air inlet flues in which the well with a single set ofdiffusers and that dampers DD are fitted. V is the-central still further unifom'ity in air distribution chimney in the lumber pile. While the might be secured b adding a third or even drawings show and the specification dea fourth set of di users. The principle, of

scribes an upwardly restricted chimney, course, remains the same and the practical 13G) expediency will determine the balance between increased uniformity of air distr'bution secured by the addition of more se of distributors and the loss in efficiency which they cause. It is also obvious that any wellknown form of distributor may be fised. The invention is 'notrestricted to the form illustrated .in which i the openings consist simply of spaces between slats running the full length of the kiln. There. may, for instance, be a number of openings of circularform, and some or all of these openings ma be dampered to permit of individual a justment of the conditions in each plenum chamber. a T

It is well understood that when the circulation of the airin the kiln is continuouslyin one direction, that portion of the pile at which the air enters will dry more rapidly, than the opposite side since the air in its passage through the lumber picks up moisture and thus reduces its drying capacity. To overcome this defect, .the direction of rotation of the fans may be reversed, thus reversing' the direction of the motion of the air through the lumber piles. This may be done periodically every two or three days or'oftener, the exact period being determined by-the condition of the lumber in the kiln.

The direction of the air travel is then as follows: Leaving the fans, the air strikes the side deflecting partitions which deflect it outward a ainst the heatin coils; passing through t e heating coils, t e air travels upward through theside air passages, inb ward through the lumber, through the 0611-.

tral chimney, downward through the central chimney through the upper diffusers and the lower diffusers, into the main air distributor, and thence back to the fans. When the air travels in this direction the heating coils serve to act as distributors, and by, the time the air leaves the .up er steam jet lines it has become distributed wlth' sufiicient uniformity. I

Having fully described the principles of this invention and the manner in which they can be embodied in a dry kiln, I claim as original 1. In a piling: a series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in said klln; and an airvdistribut ing system comprising side deflecting parti tions, a main air distributor, and two sets of diffusers.

v 2. In a dry kiln arranged for'flatwise' end piling: a. series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft ineither direction to causereversal of the circulation of the air and vapor in said kiln; dampered air inlet fines and dampered air outlet flues'; and an dry kiln arranged for flatwise end air distributing system -comprising side deflecting partitions, a main air dlstributor, and two sets of diffusers.

3. In a dry kiln arranged for flatwise end piling: a series of fans; a shaft on which the fans are mounted for rotation; means cause reversal of the circulation of the air 1 and vapor in said kiln; dampered air inlet flues and dampered air outlet'flues; means for'heating the kiln and its contents; means for humidifying the atmosphere in the kiln; and an air distributing system comprising side defi'ecting partitions, a.main air distributor, and two sets of difiusers.

5. In a dry kiln arranged for flatwise end piling: a series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in saidkiln; a plenum chamber for each fan; and a difiuser with restricted discharge passages for each plenum cham- 6. In a' dry kiln arranged for flatwise end piling: a series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of thecirculation of-the air and vapor in said kiln; dampered air inlet fiues and dampered air outlet flues; aplenum chamber for each fan; and a diffuser with restricted discharge passages for each-plenum chamber.-

j 7. In a dry kiln arrahged for flatwise-end I piling: a series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in said kilnadampered air inlet flues and dampered air outlet Hues; means for heating the kiln-and its contents; a

plenum chamber for each fan; and a diffuser I with restricted discharge passages for each plenum chamber.

8. In a dry kiln'arranged forflatwise end piling: a series of :fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation. of the air and vapor in said kiln; dampered air inlet flues and dampened.airoutlet flues; means for heating the kiln and its contents; means I forhumidifying the atmosphere in the kiln;

' a plenum chamber for each fan; and a cause reversal of the circulation of the air llO restricted discharge plenum chamber.

and vapor in said kiln; a seriesof plenum chambers for each fan; and a diffuser Wlth passages for each 10. Ina dry kiln arranged for fiatwise end piling: a series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in said kiln; dampered air inlet fines and dampered air outlet flues; a series of plenum chambers for each fan; and' a diffuser with restricted discharge passages for each plenum chamber. I

. 11. In a'dry kiln arranged for flatwise end piling: a seriesof fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in said kiln; dampered air inlet r I K I flues and dampered air outlet fines; means for heating the kiln and its contents; a series of plenum chambers for each fan; and a diffuser with restricted discharge passages for each plenum chamber.

12. In a dry kiln arranged .for fiatwise end piling: a series of fans; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and Vapor in said kiln; dampered air inlet flues and dampered air outlet flues; means for heating the kiln and its contents; means for'humidifying the atmosphere in the kiln; a series of plenum chambers for each fan;

and a diffuser with restricted discharge passages for each plenum chamber. 7

13. In an internal fan dry kiln adapted for flat end piling: a plenum chamber for each fan; and a diffuser with restricted discharge passages for each plenum chamber.

14. In an internal fan dry kiln adapted for flat end piling: a series of plenum chambers for each fan; and a diffuser with restricted discharge passages for each plenum chamber.

ROLF THELEN. 

